/*
 * 字符串加密与解密
 * */

const _keyStr = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='

// private method for UTF-8 encoding  
const _utf8_encode = string => {  
    string = string.replace(/\r\n/g,'\n');  
    var utftext = '';  
	for (var n = 0; n < string.length; n++) {  
		var c = string.charCodeAt(n);  
		if (c < 128) {  
			utftext += String.fromCharCode(c);  
		} else if((c > 127) && (c < 2048)) {  
			utftext += String.fromCharCode((c >> 6) | 192);  
			utftext += String.fromCharCode((c & 63) | 128);  
		} else {  
			utftext += String.fromCharCode((c >> 12) | 224);  
			utftext += String.fromCharCode(((c >> 6) & 63) | 128);  
			utftext += String.fromCharCode((c & 63) | 128);  
		}  

	}  
	return utftext;  
}  
const _utf8_decode = function (utftext) {  
    var string = '';  
    var i = 0;
    var c = 0;
    var c2 = 0;
	var c3 = 0;
    while ( i < utftext.length ) {  
        c = utftext.charCodeAt(i);  
        if (c < 128) {  
            string += String.fromCharCode(c);  
            i++;  
        } else if((c > 191) && (c < 224)) {  
            c2 = utftext.charCodeAt(i+1);  
            string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));  
            i += 2;  
        } else {  
            c2 = utftext.charCodeAt(i+1);  
            c3 = utftext.charCodeAt(i+2);  
            string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));  
            i += 3;  
        }  
    }  
    return string;  
} 

const Index = {
	// 加密
	encode(input){
		var output = '';  
        var chr1, chr2, chr3, enc1, enc2, enc3, enc4;  
        var i = 0;  
        input = _utf8_encode(input);  
        while (i < input.length) {  
            chr1 = input.charCodeAt(i++);  
            chr2 = input.charCodeAt(i++);  
            chr3 = input.charCodeAt(i++);  
            enc1 = chr1 >> 2;  
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);  
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);  
            enc4 = chr3 & 63;  
            if (isNaN(chr2)) {  
                enc3 = enc4 = 64;  
            } else if (isNaN(chr3)) {  
                enc4 = 64;  
            }  
            output = output +  
            _keyStr.charAt(enc1) + _keyStr.charAt(enc2) +  
            _keyStr.charAt(enc3) + _keyStr.charAt(enc4);  
        }  
        return output;
	},
	// 解密
	decode(input){
		var output = '';  
        var chr1, chr2, chr3;  
        var enc1, enc2, enc3, enc4;  
        var i = 0;  
        // input = input.replace(/[^A-Za-z0-9\+\/\=]/g, '');
		input = input.replace(/[^A-Za-z0-9+/=]/g, '');  
        while (i < input.length) {  
            enc1 = _keyStr.indexOf(input.charAt(i++));  
            enc2 = _keyStr.indexOf(input.charAt(i++));  
            enc3 = _keyStr.indexOf(input.charAt(i++));  
            enc4 = _keyStr.indexOf(input.charAt(i++));  
            chr1 = (enc1 << 2) | (enc2 >> 4);  
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);  
            chr3 = ((enc3 & 3) << 6) | enc4;  
            output = output + String.fromCharCode(chr1);  
            if (enc3 !== 64) {  
                output = output + String.fromCharCode(chr2);  
            }  
            if (enc4 !== 64) {  
                output = output + String.fromCharCode(chr3);  
            }  
        }  
        output = _utf8_decode(output);  
        return output;  
	}
}
export default Index